Solenoid



Patented Sept. 17, 1946 SOLENOID Harold J. Luth, Muskegon, Mich.,assigner to The Brunswick-Balke-Collender Company, Chicago, Ill., acorporation of Delaware Application J une 11, 1943, Serial No. 490,421

(Cl. F75- 21) Claims.

This invention relates more particularly to extremely long and slendersolenoids wherein the core and winding of `the lsolenoid are notselfsupporting.

The general object of the invention is to provide a solenoid of thistype having a rigid,vnonmetal lic shell or casing which can beconstructed about the solenoid and serve as a means of support therefor.

A more particular object of the invention is to provide a rigidsupporting structure for solenoids having high permeability cores and ahigh sensi- .tivity which is affected by deflection of the assembly.

Another object of the invention is to provide a novel method wherebysuch a rigid casing can be constructed about the solenoid. Anotherobject of the invention is to provide a solenoid with a rigid anddurable casing which will also protect the winding of the solenoid frommechanical injury, or injury due to the elements or from handling. y

A further object of the invention is to provide a solenoid with a casingwhich becomes an integral part thereof.

Other objects will become readily apparent from the following detaileddescription, taken in connection with the vaccompanying drawing, inwhich:

Fig. 1 is an elevational view of va solenoid constructed in accordancewith the invention.

Fig. 2 is an enlarged fragmentary view thereof, partly in'centralsection.

Fig. 3 is a section along the line 3--3 of Fig. 2.

Fig. 4 is a view illustrating a method of making the form of theinvention of Figs. 1 to 3.

Fig. 5 is an enlarged fragmentary View of a part of Fig. 4.

While there is illustrated in the drawing and herein described in detaila preferred form of the invention, it is to be understood that theinvention is not to be limited to the particular form and arrangementshown, it being contemplated that various modifications may be made by.those skilled in the art Without departing from the spirit and scope ofthe invention as set forth in the appended claims.

In Figs. 1 to 3 of the drawing there is illustrated a solenoid having ahigh permeability core I0, ends II, a Winding I2, and a casing I3. Inthis form of the invention the casing I3 is Wound in layers onto thesolenoid winding and consists of several turns I4 of resin impregnatedpaper or cloth, several additional turns of impregnated paper or clothwith wood veneer I5 interleaved,

the grain of the wood veneer running lengthwise of the solenoid, `andlastly, additional layers of impregnated paper or cloth, or both.

Preferably a high tensile spinning paper is used which has beenimpregnated with an amount of heat-setting phenol formaldehyde resinequal to about 35 percent of the Weight of the paper. A heat-settingphenol formaldehyde resin which is soluble in a solvent such as alcoholor water, and which can be evaporated olf, may be used for lthispurpose. A resin manufactured by the Bakelite Corporation and identiedby their number XVl'6238 has been used successfully. By paper which hasbeen impregnated is meant paper which may be coated on one side, or bothsides, or entirely filled with resin. The veneer is preferably coated ontwo sides.

Fig. 4 illustrates the manner in which the casing I3 may be applied .tothe solenoid winding. A sheet of paper I4, coated with a suitable resin20 (Fig. 5) on its upper side, has been wound onto the solenoid coiluntil there are several turns of the paper on the winding. Veneer I5coated with resin on its surfaces at 2| has been placed upon the uppercoated surface of the paper I4 in position so .that as the winding ofthe paper onto the solenoid continues, there is placed on the solenoidseveral turns of veneer separated by the sheet of .paper I4 whichextends continuously to the end 22. As the winding operation continues,additional layers `of resin coated paper are applied on top of theveneer-paper layers so that the outer portion of the casing consists ofseveral layers of the paper. The entire assembly is then cured underheat and pressure, Vas by jacketing the assembly in a sheet of rubberwhich lhas been relongated from to 200 per cent and `applied undertension, and thereafter placed in an oven ata .temperature of 250 F. fora period of two hours, utilizing the process disclosed in a .co-pendingapplication, Serial No. 483,540, filed April 19, 1943, by Harold J.Luth, Herman B. Scheidemantel and Sydney R. Krupnick.

In the event that the solenoid is to have an outer casing of cloth asdescribed immediately hereafter, the squeezing effect obtained byjacketing the solenoid in rubber can be very nearly duplicated bytightly Winding the last layer of cloth in a spiral under tension,securely fastening the two ends and then curing. During the curingoperation the cloth jacket will tend to shrink and harden about theentire assembly, making the mass compact. Although .this method can beused, for extreme rigidity `and 3 hardness the method using a rubberjacket is preferred.

The solenoid constructed as herein disclosed is extremely rigid andadequately protected against mechanical injury or injury due to theelements or from handling. A solenoid constructed in accordance with theinvention, 21/2'l in diameter and 6' long and containing 6l) pounds ofcopper wire and core, has been wound with four turns of impregnatedpaper, followed by four complete turns of paper and veneer, siX turns ofpaper and one turn of impregnated cloth on the outside. A solenoid soconstructed and thereafter cured as hereinbefore specified, whensupported at its two ends, had a deflection at the center on the orderof als of an inch. Under the method herein set forth the entire assemblybecomes an integral unit and the solenoid is entirely self-supporting.

During the entire process the solenoid is preferably supported on a flattable or on parallel rollers or other suitable means which will preventdistortion or deflection until the curing and setting operations arecompleted.

In using phenol formaldehyde resins or ce* ments, approximately 4% of anacid or alkaline catalyst is used to bring about the hardening. Althoughan adhesive or resin of the type hereirrbefore set forth is satisfactoryandvdesirable,

it is not intended `to limit the invention to the use of any particularresin or combining agent. It would be possible, for example, to make asimilar solenoid casing by using urea formaldehyde bonding agents whichare thermo-setting, or by using shellac which is thermo-plastic. In thecase of a shellac, however, it would be necessary to cool the solenoidwhile it is hung in a vertical position.

.As a veneer, birch and maple have been used. Obviously other types ofwood and other lowdensity, high-tensile value materials might be used tomake a casing having suitable rigidity. An impregnated cloth can readilybe substituted for paper. If an extreme degree of waterproof- `ness isdesired, the veneer can first be treated by saturation with a phenolresin dissolved in alcohol, or by use of a hydrophilic resin in water inthe same manner as wood is treated for impregnating wood, a process wellknown in the art. In the examples hereinbefore given, the paper wasapproximately .005 of an inch in thickness, Vand the veneer was .05 ofan inch, the resulting casing being approximately 1/8 of an inch thick.

I claim as my invention:

l. A solenoid comprising a core, an insulated winding thereon, meansoutside of said winding and surrounding it comprising a sheet ofmaterial impregnated with a heat-setting resin wound around the windingin layers, and a thin sheet of wood wound intermediate certain layers ofsaid impregnated material and with its grain running parallel to theaxis of the solenoid to reinforce winding and preventing flexure of thesolenoid Y lwhen supported in a horizontal position and by its ends,comprising a sheet of paper impregnated with a heat-.setting phenolformaldehyde resin wound in tight layers over the outer layers of saidWinding and a sheet of resin impregnated thin wood reinforcing materialwound between a pluralityof layersv of said paper with its fibersextending mainly lengthwise of the solenoid, said enclosing means beingsubjected to heat to cause the resin to set and operating to stiffenthe' solenoid and prevent bending thereof.

3. A solenoid comprising a long central core, an insulated windingaround said coreand means enclosing the winding comprising a sheet ofpaper impregnated with a heat-setting phenol formaldehyde resin wound intight layers over the outer surface of said winding, and a sheet ofresin impregnated wood wound between con'- secutive layers of said paperwith its fibers extending longitudinally of the solenoid and operatingto stiffen the solenoid and prevent bending thereof when said enclosingmeans has been subjected to heat to cause the resin to set.

4. A solenoid comprising a long central core, an insulated windingaround said core, and means enclosing the winding comprising a sheet ofcloth impregnated with a heat-setting phenolforrnaldehyde resin wound intight layers over the outer surface of said Winding, and a thin vsheetof reinforcing wood material wound between ntermediate layers of saidcloth and operating to stiffen the solenoid and prevent bending thereofwhen said enclosingv means has been subjected to heat to cause the resinto set.

5. A solenoid comprising a relatively long cylindrical core, a Windingon said core comprising a plurality of layers of insulated wire `and ofsubstantial weight, and means for enclosing the winding and preventingiiexure of the solenoid when supported in a horizontal position and byits ends, comprising a sheet of thin sheet ,material impregnated with aheat-setting phenol formaldehyde resin Wound in tight layers over theouter layer of said winding, and a sheet of wood woundA betweenconsecutive layers of said thin sheet material and operating toI stiienthe solenoid and prevent bending thereof when said enclosing means hasbeen subjected to heat to cause the resin to set.

HAROLD J. LUTH.

